#[cfg(test)]
mod tests {
    #[test]
    fn scalar() {
        let tup: (i32, f64, u8) = (500, 6.4, 1);
        let (x, y, _) = tup;

        println!("tup {:?}", tup);
        println!("tup.0 {}", tup.0);

        let s1 = String::from("hello");
        //多返回值
        let (s2, len) = calculate_length(s1);
    }

    fn calculate_length(s: String) -> (String, usize) {
        let length = s.len(); // len() 返回字符串的长度
        (s, length)
    }
}
